The Catalytic Mechanism of Electron-Bifurcating Electron Transfer Flavoproteins (ETFs) Involves an Intermediary Complex with NAD\u3csup\u3e+\u3c/sup\u3e

Electron bifurcation plays a key role in anaerobic energy metabolism, but it is a relatively new discovery, and only limited mechanistic information is available on the diverse enzymes that employ it. Herein, we focused on the bifurcating electron transfer flavoprotein (ETF) from the hyperthermophilic archaeon Pyrobaculum aerophilum. The EtfABCX enzyme complex couples NADH oxidation to the endergonic reduction of ferredoxin and exergonic reduction of menaquinone. We developed a model for the enzyme structure by using nondenaturing MS, cross-linking, and homology modeling in which EtfA, -B, and -C each contained FAD, whereas EtfX contained two [4Fe-4S] clusters. On the basis of analyses using transient absorption, EPR, and optical titrations with NADH or inorganic reductants with and without NAD+, we propose a catalytic cycle involving formation of an intermediary NAD+-bound complex. A charge transfer signal revealed an intriguing interplay of flavin semiquinones and a protein conformational change that gated electron transfer between the low- and high-potential pathways. We found that despite a common bifurcating flavin site, the proposed EtfABCX catalytic cycle is distinct from that of the genetically unrelated bifurcating NADH-dependent ferredoxin NADP+ oxidoreductase (NfnI). The two enzymes particularly differed in the role of NAD+, the resting and bifurcating-ready states of the enzymes, how electron flow is gated, and the two two-electron cycles constituting the overall four-electron reaction. We conclude that P. aerophilum EtfABCX provides a model catalytic mechanism that builds on and extends previous studies of related bifurcating ETFs and can be applied to the large bifurcating ETF family

A systematic review of the association between nursing staff and nursing-sensitive outcomes in long-term institutional care

Aims To examine the association between type of nursing staff and nursing-sensitive outcomes in long-term institutional care. Design This systematic review included studies published in English, German, and Dutch between January 1997 and January 2020. Data sources The databases Medline (PubMed), CINAHL, PsycINFO, Embase, and the Cochrane Library were searched. Original quantitative studies were included. Review methods The Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines were followed. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist was used to critically appraise the reporting of the studies. Results Fifteen articles were included. Of 33 quality of care outcomes, 21 were identified as nursing-sensitive outcomes of which 13 showed a significant association with nursing staff, specifically: Activities of daily living, aggressive behavior, bladder/bowel incontinence, contractures, expressive language skills, falls, infection (including vaccination), range of motion, pain, pressure ulcers, and weight loss. However, studies reported inconsistent results regarding the association among RNs, LPNs, CNAs, and HCAs and these nursing-sensitive outcomes, evidence shows that more RNs have a positive impact on nursing-sensitive outcomes. As to the evidence regarding the other type of nursing staff, especially HCA, findings regularly showed a negative association. Conclusion Future research should be expanded with structure and process variables of which the mediating and moderating effect on nursing-sensitive outcomes is known. These may explain variances in quality of care and guide quality improvement initiatives. Researchers should consider fully applying Donabedian's structure-process-outcomes framework as it is a coherent entirety for quality assessment. Impact This review provides an overview of quality of care outcomes that are responsive to nursing interventions in long-term institutional care. As the effects can be monitored and documented, quality assessment should focus on these nursing-sensitive outcomes. The inconclusive results make it difficult to provide recommendations on who should best perform which care

Fertilizing Nature: A Tragedy of Excess in the Commons

Why has nitrogen fertilizer use declined in some countries while increasing in others, despite significant environmental harm? Proper crop management strategies offer environmental and economic benefits without sacrificing yields

Improving Nursing Home Care through Feedback On PerfoRMance Data (INFORM): Protocol for a cluster-randomized trial

Background Audit and feedback is effective in improving the quality of care. However, methods and results of international studies are heterogeneous, and studies have been criticized for a lack of systematic use of theory. In TREC (Translating Research in Elder Care), a longitudinal health services research program, we collect comprehensive data from care providers and residents in Canadian nursing homes to improve quality of care and life of residents, and quality of worklife of caregivers. The study aims are to a) systematically feed back TREC research data to nursing home care units, and b) compare the effectiveness of three different theory-based feedback strategies in improving performance within care units. Methods INFORM (Improving Nursing Home Care through Feedback On PerfoRMance Data) is a 3.5-year pragmatic, three-arm, parallel, cluster-randomized trial. We will randomize 67 Western Canadian nursing homes with 203 care units to the three study arms, a standard feedback strategy and two assisted and goal-directed feedback strategies. Interventions will target care unit managerial teams. They are based on theory and evidence related to audit and feedback, goal setting, complex adaptive systems, and empirical work on feeding back research results. The primary outcome is the increased number of formal interactions (e.g., resident rounds or family conferences) involving care aides – non-registered caregivers providing up to 80% of direct care. Secondary outcomes are a) other modifiable features of care unit context (improved feedback, social capital, slack time) b) care aides’ quality of worklife (improved psychological empowerment, job satisfaction), c) more use of best practices, and d) resident outcomes based on the Resident Assessment Instrument – Minimum Data Set 2.0. Outcomes will be assessed at baseline, immediately after the 12-month intervention period, and 18 months post intervention. Discussion INFORM is the first study to systematically assess the effectiveness of different strategies to feed back research data to nursing home care units in order to improve their performance. Results of this study will enable development of a practical, sustainable, effective, and cost-effective feedback strategy for routine use by managers, policy makers and researchers. The results may also be generalizable to care settings other than nursing homes. Trial registration ClinicalTrials.gov Identifier: NCT02695836 . Date of registration: 24 February 201